As regards a controller that adjusts acceleration or deceleration or maximum speed by changing a speed pattern or the like assigned to a motor used in an elevating machine or the like, depending on load or moving distance, there have been developed controllers for preventing an equipment from being thermally overloaded.
An art concerning a conventional elevator controller of this kind is disclosed in, for example, JP 2002-3091 A. This controller includes a main control unit for performing an operation control of the elevator, a power drive unit for driving a motor, and a thermal sensing device installed for an equipment that is getting hot when the elevator is being operated. The main control unit suppresses temperature rise of the equipment by performing a load suppressing operation on the basis of temperature detection results of the thermal sensing device before the equipment becomes inoperable due to overheating, thus preventing the equipment from becoming inoperable. In this conventional art, a determination on a load state of the equipment is made through a comparison between a temperature detection result or its rate of change and a critical temperature of the equipment, and a changeover to the load suppressing operation is made, so that the equipment is prevented from becoming inoperable.
Further, a conventional controller that adjusts acceleration or deceleration and maximum speed of a motor depending on load is disclosed in, for example, JP 7-163191 A. An elevator controller that adjusts acceleration or deceleration by changing a speed pattern or the like assigned to a motor depending on load and a moving distance is disclosed in JP 9-267977 A.
In the aforementioned conventional apparatuses, a temperature rise of the equipment is suppressed by making a changeover to the load suppressing operation before the equipment reaches a drive-permitting critical temperature, to thereby prevent deterioration in running efficiency resulting from inoperability of the equipment. However, since a timing at which the changeover to the load suppressing operation takes place is determined based on an output result of the thermal sensing device or its temporal rate of change, a total amount of the temperature rise in the end cannot be estimated with accuracy. Therefore, the changeover timing to the load suppressing operation is not always appropriate, which results in a problem in that running efficiency is deteriorated.